The present invention generally relates to a system and method for improved cardiac image alignment. Particularly, the present invention relates to a system and method for temporally aligning a plurality of cardiac image sequences.
Medical diagnostic imaging systems encompass a variety of imaging modalities, such as x-ray systems, computerized tomography (CT) systems, ultrasound systems, electron beam tomography (EBT) systems, magnetic resonance (MR) systems, positron emission tomography (PET), single photon emission computed tomography (SPECT), and the like. Medical diagnostic imaging systems generate images of an object, such as a patient, for example, through exposure to an energy source, such as x-rays passing through a patient, for example. The generated images may be used for many purposes.
One example for using the images generated by medical diagnostic imaging systems is for cardiac imaging. Several cardiac imaging techniques permit physicians to take a closer look at the heart and vessels with minimal risk to the patient. Different modalities, such as CT, EBT, MR, PET or SPECT, provide complementary information about temporal structures and pathologies. Cardiac images of a patient may be acquired using the same modality at different times or using different modalities and different times. Dynamic cardiac images acquired at different times may be considered five dimensional, for example dynamic 3D images may be considered four dimensional. Four dimensional images that are acquired at multiple times may be considered five dimensional. Typical examples may include dynamic cardiac CT scans and/or gated cardiac MRI scans acquired at 3-monthly intervals. Another example may include dynamic cell growth and shape change examinations in weekly intervals.
The combination of information from multiple cardiac image modalities, for example MRI and CT, is of increasing interest in the medical community for physiologic understanding and diagnostic purposes. It is difficult, however, to fuse information from multiple dynamic clinical images, especially when the clinical images are captured at different time points, with different modalities and with different setups.
For example, because of the rapid progresses in imaging techniques, the amount of image data involved in a comprehensive patient study is massive. Gated cardiac MRI or CT sequences recorded from a complete cardiac cycle, for example, comprise 1500-5000 two dimensional images and pose challenges to archiving, storage and data transfer. Alignment of inter-modality and/or intra-modality images is also challenging because images are captured in various orientations and positions and at different scales. Typically, it is a time consuming process to manually align the data. Generally, gating techniques used in the clinical environment, coupled with noise and error, are not consistent with each other. For example, peripheral-gated images are usually delayed with respect to precordial-gated images. Moreover, gating information is usually not available when these images are inspected. Also, different temporal resolutions are used for different modalities and different diseases. These, among other problems, present a need for improved cardiac image alignment.